/*
 * R : A Computer Language for Statistical Data Analysis
 * Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 * Copyright (C) 1997--2008  The R Development Core Team
 * Copyright (C) 2003, 2004  The R Foundation
 * Copyright (C) 2010 bedatadriven
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.renjin.primitives.special;

import org.renjin.eval.Context;
import org.renjin.sexp.Environment;
import org.renjin.sexp.FunctionCall;
import org.renjin.sexp.Null;
import org.renjin.sexp.PairList;
import org.renjin.sexp.SEXP;
import org.renjin.sexp.SpecialFunction;

public class IfFunction extends SpecialFunction {

  public IfFunction() {
    super("if");
  }

  @Override
  public SEXP apply(Context context, Environment rho, FunctionCall call, PairList args) {
    SEXP condition = context.evaluate( call.getArguments().getElementAsSEXP(0), rho);

    if (asLogicalNoNA(context, call, condition)) {
      return context.evaluate( call.getArguments().getElementAsSEXP(1), rho); /* true value */

    } else {
      if (call.getArguments().length() == 3) {
        return context.evaluate( call.getArguments().getElementAsSEXP(2), rho); /* else value */
      } else {
        context.setInvisibleFlag();
        return Null.INSTANCE;   /* no else, evaluates to NULL */
      }
    }
  }
}
